In recent years magnetic recording media for audio, video or computer use which enable a large amount of information to be recorded in a small area thereof have been required. In addition, a smoothing finish has been added to the surfaces of their magnetic layers for the purpose of improvement upon the sensitivity, (especially, in a high frequency region), and that, they are formed into thin tapes having a thickness of about 20 .mu.m or less. Accordingly, their backing layers are also thin, and tend to come off, at least partially. Further, thinning magnetic tapes results in lowering their overall strength, which has adverse effects upon running durability, take-up characteristics, drop out, fluctuation of output and so on.